Device and method for ablation of tissue

Abstract

A device and method for performing electrolyte assisted tissue ablation of metaplasia in the esophagus includes a shaft with an expandable barrier which is deployable from the shaft's distal end. Also included in the device are an electrode and a temperature/impedance sensor which are each mounted on the shaft. Alternatively, the shaft may be a catheter formed with several lumens which are used independently for housing optical elements and for transferring fluid. In the operation of the device, the distal end of the shaft or catheter is placed in the esophagus proximal the cardia. The barrier is then deployed to the cardia and expanded to seal the esophagus from the stomach. The esophageal volume between the barrier and the catheter is partially flooded with a conducting medium and an electrode is deployed into the conducting medium. The sensor is also deployed into contact with the tissue to be ablated. Using open-loop control, or using temperature, impedance, or visual monitoring for closed-loop control, the metaplasia is ablated by passing radio frequency energy from the electrode and through the conducting medium for contact with the tissue being ablated.

What is claimed is: 
     
       1. A device for ablating selected tissue of a body cavity which comprises: a shaft;   a barrier mounted on said shaft for creating a volume in the body cavity, said volume being at least partially bounded by said barrier and the selected tissue of the body cavity;   a conductive medium introduced into a portion of said volume to contact the selected tissue;   an electrode submersible in said conductive medium;   a radio frequency generator connected to said electrode for applying radio frequency energy through said conductive medium to ablate the selected tissue; and   a porous carrier mounted on said shaft and wherein said carrier is filled with said conductive medium, and wherein said barrier is mounted on said shaft distal to said carrier to substantially prevent a flow of conducting medium from said volume distally to said barrier.   
     
     
       2. A device as recited in claim 1 wherein said conductive medium is an electrolytic solution containing saline. 
     
     
       3. A device as recited in claim 1 wherein said conductive medium is a gel. 
     
     
       4. A device as recited in claim 1 further comprising: means for monitoring ablation of the selected tissue; and   means for stopping the application of said radio frequency when a predetermined amount of the selected tissue has been ablated.   
     
     
       5. A device as recited in claim 4 wherein said monitoring means includes an impedance measurement means. 
     
     
       6. A device as recited in claim 4 wherein said monitoring means comprises: illuminating means for illuminating the selected tissue bounding the volume in the body cavity; and   imaging means for viewing the illuminated tissue in the body cavity.   
     
     
       7. A device as recited in claim 4 wherein said monitoring means includes at least one temperature probe for contact with the selected tissue. 
     
     
       8. A device as recited in claim 7 further comprising a depth stop mounted on said probe for deploying said temperature probe into the selected tissue to a pre-determined depth. 
     
     
       9. A device as recited in claim 8 further comprising a barb attached to said probe for securely holding said probe in the selected tissue. 
     
     
       10. A device as recited in claim 7 wherein said probe is helical shaped for screwing said probe into the selected tissue to securely hold said probe in the selected tissue. 
     
     
       11. A device as recited in claim 1 wherein said barrier is an inflatable balloon. 
     
     
       12. A device as recited in claim 1 wherein said barrier is a first barrier and said device further comprises a second barrier, wherein said second barrier is distanced from said first barrier to establish said volume therebetween. 
     
     
       13. A device as recited in claim 1 further comprising a porous carrier mounted on said shaft and wherein said carrier is filled with said conductive medium. 
     
     
       14. A device as recited in claim 1 wherein said porous carrier is made of an open cell sponge-like material. 
     
     
       15. A device as recited in claim 1 further comprising a grounding means for receipt of said radio frequency energy after said radio frequency energy passes through said conductive medium and said selected tissue. 
     
     
       16. A method as recited in claim 1 further comprising the steps of: monitoring ablation of the selected tissue; and   stopping said radio frequency energy when a predetermined amount of the selected tissue has been ablated.   
     
     
       17. A method as recited in claim 16 wherein said monitoring step further comprises the steps of: illuminating the selected tissue bounding the volume in the body cavity; and   imaging the illuminated tissue in the body cavity.   
     
     
       18. A method as recited in claim 16 wherein said monitoring step further comprises the steps of: inserting at least one temperature probe into the selected tissue; and   determining when the temperature of the selected tissue indicates a predetermined amount of the selected tissue has been ablated for initiation of said stopping step.   
     
     
       19. A method as recited in claim 16 wherein said monitoring step is accomplished by measuring impedance of the selected tissue. 
     
     
       20. A method for ablating selected tissue of a body cavity which comprises the steps of: using a barrier mounted on a shaft for creating a volume in the body cavity, said volume being at least partially bounded by said barrier and the selected tissue of the body cavity, and wherein a porous carrier is mounted on said shaft with said barrier mounted on said shaft distal to said carrier;   introducing a conductive medium into said volume to fill said porous carrier with said conductive medium and contact the selected tissue with said conductive medium, said barrier substantially preventing the flow of said conducting medium from said volume distally to said barrier;   submersing an electrode in said conductive medium; and   sending radio frequency energy through said conductive medium to ablate the selected tissue.   
     
     
       21. A device for ablating selected tissue of a body cavity which comprises: a shaft;   a barrier mounted on said shaft for creating a volume in the body cavity, said barrier being a flexible resilient disk, said volume being at least partially bounded by said barrier and the selected tissue of the body cavity;   a conductive medium introduced into a portion of said volume to contact the selected tissue;   an electrode submersible in said conductive medium;   a radio frequency generator connected to said electrode for applying radio frequency energy through said conductive medium to ablate the selected tissue.   
     
     
       22. A device for ablating selected tissue of a body cavity which comprises: a shaft;   a barrier mounted on said shaft for creating a volume in the body cavity, said barrier is made of a closed cell sponge-like material, said volume being at least partially bounded by said barrier and the selected tissue of the body cavity;   a conductive medium introduced into a portion of said volume to contact the selected tissue;   an electrode submersible in said conductive medium; and   a radio frequency generator connected to said electrode for applying radio frequency energy through said conductive medium to ablate the selected tissue.